Whisk together 4 tablespoons of the milk with the flour. The slurry will be somewhat thick, make sure all lumps are removed.
Add in the rest of the milk and transfer the mixture to a pot.
Simmer the mixture over medium heat, whisking constantly. As bubbles begin to come up and steam, remove the pot and continue to stir for another 30 seconds.
Cover the milk mixture (either in the pot or put into a bowl) with plastic wrap pressed directly against the surface so that no skin forms. Cool for 15 to 30 minutes.
In a mixer with the paddle attachment, combine the butter, sugar, lemon zest, and vanilla fitted with the beating on high speed for about to 5 minutes
Scrape the sides and add the cooled milk mixture continuing to beat on high speed until the filling is smooth, another 5 minutes or so.
Beat in the ricotta cheese 1 tablespoon at a time.
Preheat your oven to 335F. Coat three 9 inch spring form pans with butter and dust with flour, coating up the sides so the cakes do not stick.
Measure the flour, cornstarch, baking powder, and salt into one bowl, and the milk and vanilla into a separate bowl. Whisk each to combine.
In the standing mixer fitted with the wire whip attachment, beat the egg whites on high speed to a stiff peak. Drizzle in 1 cup of the sugar while the mixer is running.
Scoop the meringue into a large bowl and set aside.
Wipe the mixer bowl and replace the wire whip with the paddle attachment. Cream the butter with the remaining 1 cup of sugar on low speed. Add the egg yolks one at a time. Scrape the sides of the bowl and mix on low speed until the ingredients are thoroughly combined.
Add the dry and wet ingredients alternating about a quarter at a time and don't pause between additions.
Stop the mixer and gently fold the meringue into the batter with a spatula.
Pour the mixture evenly into the pans and bake for 27 to 30 minutes, or until the cake bounces back when lightly pressed and a wooden skewer inserted in the center comes out clean.
Cool the cakes for a few minutes, then invert the cakes onto a flat surface. They will be very fragile, so handle them with care.
To assemble the cake by adding about 1 cup each of the fresh strawberries and the ricotta filling between the layers.
Cover the outside of the cake with the sweetened whipped cream.* Add more fresh strawberries around the edge of the cake